472 BIOLOGY OF PNEUMOCOCCUS 



result during the acute stages of the disease but a positive reac- 

 tion appears late in the period of convalescence (Abernethy and 

 Francis 2 ). The reaction in this case is of the delayed variety, not 

 appearing until several hours after the injection is made, and im- 

 munologically is species-specific and not type-specific. 



When the somatic C polysaccharide of Pneumococcus is em- 

 ployed, a positive cutaneous reaction may be obtained in the great 

 majority of patients during the acute stages of the disease and 

 has been demonstrated as early as twelve hours after the initial 

 chill. The state of reactivity to the C Fraction usually persists 

 throughout the acute febrile period. With the onset of recovery, 

 whether associated with crisis or lysis, the reaction decreases 

 markedly in intensity and, during an uncomplicated convalescence, 

 in the majority of instances can no longer be demonstrated. Reac- 

 tivity may persist or reappear if complications develop. If the 

 case terminates fatally, the patient may fail to give a skin reac- 

 tion to the somatic carbohydrate during some stage of the acute 

 disease (Abernethy and Francis). The local manifestations ap- 

 pearing after the intradermal injection of the C Fraction occur in 

 a positively reacting person within fifteen to twenty minutes and 

 in their early development resemble those of the capsular polysac- 

 charide skin test, but the zone of erythema is less intense and 

 pseudopods extending out from the central wheal, so frequently 

 seen in the latter, are rarely encountered. Within an hour the 

 acute phase has usually passed and is then followed by a delayed 

 reaction, an edematous erythema. The delayed reaction begins to 

 appear in two to three hours, is well marked in six to ten hours, 

 persists for eighteen to twenty-four hours, and then fades, leaving 

 a residual brown stain (Abernethy and Francis). The C polysac- 

 charide, being common to all pneumococci, is heterogenetic in its 

 capacity to elicit a positive reaction in the skin of pneumonia pa- 

 tients and, furthermore, cutaneous reactivity to this carbohydrate 

 component of pneumococci is not limited to patients infected with 



